1. Technical Field
The present invention relates to an optical waveguide and a method for manufacturing the same.
2. Related Art
The technology of high speed transmission of signals using electricity is approaching its limit because of crosstalk, high power consumption, high loss and the like, and therefore, there are great expectations in the role of optical transmission. A long-distance optical transmission has been standardized by means of a single-mode quartz-based optical fiber from the viewpoint of low-loss characteristics, high reliability and the like, while in a short-distance optical transmission, transmission using electricity has been principally carried out from the viewpoint of costs for connection or difficulty of handling, thereby causing a bottle neck.
In these situations, it has been expected that a multi-mode polymeric optical waveguide might be applied to the short-distance optical transmission from the viewpoint of low costs, easy handling such as simple and easy connection, and high flexibility, although the above-described optical waveguide provides a slightly larger optical power loss compared to the quartz-based optical fiber.
Several methods of manufacturing a multi-mode polymeric optical waveguide have been proposed as described below.
(1) A method in which a film is impregnated with a monomer, a core part is selectively exposed to UV ray to change its refractive index and the film is then attached to another material (a selective polymerization method).
(2) A method in which a core layer and a cladding layer are applied and then a cladding part is formed by using reactive ion etching (an RIE method).
(3) A method in which an ultraviolet ray-curable resin obtained by adding a photosensitive material into a polymer material is exposed and developed by photolithography (a direct exposure method).
(4) A method using injection molding.
(5) A method in which a core layer and a cladding layer are applied and then a core part is exposed to UV ray to change the refractive index of the core part (a photo-bleaching method).
(6) A method using a silicon rubber mold.